Illustration by J. MacGown, Mississippi State University

• Worker is 1/16 to 1/8 inch long (2.2-3.2 mm)
• Single small node, but hidden by base of abdomen
• Antenna 12 segmented, without a club
• Thorax uneven, without spines
• No stinger, and no acidopore (a circle of hairs around the orifice at tip of abdomen)

• Uniform color
• Brown to black

Argentine ant (Linepithema humile)

• Feeds mainly on sweets, tends aphids and mealybugs on plants and feeds on honeydew and plant juices
• Feeds also on seeds, live or dead insects, and greasy foods like meats, cheeses, oils
• Outdoors: nests in soil under stones, logs, patios, debris piles; also under bark, in plant cavities, in animal nests
• Indoors: nests in wall voids, under floors, around heaters and hot water pipes; also in crevices behind base-boards, cabinets, window sills, etc.

• Worker follows trails along foundations, sidewalks, tree branches, baseboards, and carpet edges
• Colonies can be large with many queens
• Has rotten coconut odor when crushed
• When alarmed, worker runs erratically with abdomen raised
• Swarms from May to mid-July
• May move indoors when honeydew supply drops, in fall, or during rains

Photo by Marlin E. Rice
Iowa State University Extension